MyAgeCalc

Lean body mass calculator

Lean body mass is your weight minus your fat. For a 5′10″, 176 lb man the Boer formula gives about 134 lb (76%).

Height
Lean body massBoer formula
106

lb lean, which is 71% of your weight. Estimated fat mass: 44 lb (29%).

FormulaLean massBody fat
Boer (1984)106 lb (71%)29%
James (1976)107 lb (71%)29%
Hume (1966)103 lb (69%)31%

Estimates for general information, not medical advice. Talk to a doctor or dietitian about your own health.

The three formulas

Boer (1984) men: 0.407 × weight (kg) + 0.267 × height (cm) − 19.2; women: 0.252 × weight + 0.473 × height − 48.3.

James (1976) men: 1.1 × weight − 128 × (weight ÷ height)²; women: 1.07 × weight − 148 × (weight ÷ height)².

Hume (1966) men: 0.32810 × weight + 0.33929 × height − 29.5336; women: 0.29569 × weight + 0.41813 × height − 43.2933.

Formula or measurement?

The formulas only know your height and weight, so two people with the same numbers get the same answer even if one lifts weights and the other doesn't. If you have a body-fat reading from a DEXA scan, calipers or a smart scale, type it in: the result then uses your real fat percentage.

Compare with your ideal weight range, or see how many calories your lean frame burns in the calories burned calculator.

Questions

What is lean body mass?

Everything in your body that isn't fat: muscle, bone, organs, skin, blood and water. It is total weight minus fat mass, so it is always the larger share of your weight.

Which lean body mass formula is best?

The Boer formula (1984) is the one most often recommended for adults of normal weight. The James formula overestimates in people with obesity — it can even fall as weight rises — so we flag it when your BMI is above 35. All three are estimates; a DEXA scan or bioimpedance gives a measured value.

What is a normal lean body mass percentage?

For most healthy adults lean mass is roughly 70–90% of body weight for men and 65–85% for women, because typical body fat runs about 10–30% and 15–35% respectively. Athletes sit at the top of those ranges.

How do I calculate lean body mass from body fat percentage?

Multiply your weight by (100 − body fat %) ÷ 100. At 80 kg and 20% body fat, lean mass is 80 × 0.8 = 64 kg. Enter a body fat percentage above to use this method instead of the formulas.

Why does lean body mass matter?

Lean mass drives your resting energy use, and some medicines are dosed on it. Tracking it while dieting shows whether you are losing fat or muscle.

Sources

  • Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. Am J Physiol, 1984.
  • James WPT. Research on obesity. HMSO, London, 1976. Hume R. Prediction of lean body mass from height and weight. J Clin Pathol, 1966.